This standard defines the syntax and semantics of the VHSIC Hardware Description Language (VHDL). The acronyms@ VHSIC (Very High Speed Integrated circuits)@ in the language's name comes from the U.S. government program that funded early work on the standard. PURPOSE VHDL is a formal notation intended for use in all phases of the creation of electronics systems. Since it is both machine and human readable@ it supports the design@ development@ verification@ synthesis@ and testing of hardware designs; the communicationof hardware design data; and the maintenance@ modification@ and procurement of hardware.This document is intended for the implementers of tools supporting the language and for advanced users of the language.